1. Field of the Invention
The present invention relates generally to tracked vehicles. More particularly, the present invention relates to a tracked bicycle for use on snow, sand, mud, etc.
2. Related Art
Mountain biking, off-road bicycling, and/or bicycling in and around nature have become popular sports or pastimes. Bikers or cyclists often enjoy riding in wilderness or natural environments, such as the woods, sand dunes, red-rocks, etc. Such environments can provide a welcome change from city or suburban environments. In addition, such environments can provide unique and challenging riding conditions, including steep uphill climbs, steep downhill descents, sharp curves, etc. Some wilderness or natural environments are provided with bike trails. Such trails can be simple paths in the dirt or sand, while others can be graded or covered with gravel, while still others may be paved. Another unique and challenging riding condition of the wilderness or natural environments is obstacles, such as larger rocks, fallen tree trunks, streams and rivers, mud, sand dunes, etc. These natural conditions provide additional enjoyment and challenge to the cycling experience.
Such bicycling or cycling is often dependent on weather conditions, or seasons. While some areas or locations allow for year-round riding, other areas can be limited to the spring, summer and fall months. For example, many popular riding areas are located in the mountains, where annual winter snowfall prohibits riding off-road or on non-maintained trails. In addition, it will be appreciated that most maintained roads are for motor vehicles, and that sharing a road with such motor vehicles in winter conditions can be extremely dangerous. Therefore, even the most ardent mountain bikers tend to store their bikes for the winter and opt for either in-door stationary bicycles, alternative winter sports such as snowshoeing or cross-country skiing, or simple waiting out the winter.
Some efforts have been made to continue mountain biking in the winter. For example, bicycles have been proposed with xe2x80x9cfatxe2x80x9d or wide tires to prevent sinking into the snow. Such bicycles have special, wide frames to accommodate the fat or wide tires. Thus, the rider must invest in another bicycle with this approach. As another example, standard mountain bikes have been proposed with special tires that have spikes or studs. Such tires tend to be thin enough to sink into the snow. As a further example, devices have been proposed with a seat disposed on front and rear skis. Such devices, however, are suitable only for coasting down a slope, and are not provided with any means of propulsion.
Various tracked, off-road, recreational vehicles have been proposed. Such vehicles have a continuous track, similar to tank tracks, as opposed to, or in addition to, wheels. While some tracks have been used for motor powered vehicles, such as all-terrain-vehicles (ATVs), it is not readily apparent how to adapt such tracks for use with human-powered vehicles, such as bicycles. Some tracks have been proposed for use with human-powered vehicles, but are cumbersome, awkward, and require special modifications to the bicycle.
In addition, other areas or locations have riding conditions for which typical mountain bikes are ill suited. For example, mud and sand can be as difficult to ride in as snow. Tires tend to slip and spin in both mud and sand. In addition, the tires can sink into both mud and sand.
It has been recognized that it would be advantageous to develop a bicycle capable of being realistically operated in conditions or environments such as snow, mud, sand, etc. In addition, it has been recognized that it would be advantageous to develop a bicycle with improved traction and buoyancy with respect to the riding surface. In addition, it has been recognized that it would be advantageous to develop a bicycle which can be operated in different conditions, or which can be easily converted for use in different conditions, such as both hard dirt and snow.
The invention provides a tracked vehicle, or a kit for converting a standard bicycle into a tracked vehicle, with improved traction and buoyancy characteristics on certain soft riding surfaces, such as snow, mud, sand, etc. The vehicle or bicycle can have a frame with a rear fork (or rear stays), a rear axle location, and a drive assembly. The kit advantageously allows a standard bicycle to be configured as both a wheeled vehicle, and a tracked vehicle.
The vehicle or kit advantageously includes a track assembly with a continuous track movably disposed around a drive wheel and a bogie wheel. The drive wheel is coupled to the frame or rear fork at the rear axle location. The bogie wheel of the track is disposed rearward of the drive wheel, and maintains the track against the riding surface.
In addition, the vehicle or kit advantageously includes a bogie apparatus to bias the bogie wheel and the track against the riding surface. One or more compliant and resilient arms advantageously are operatively coupled to the frame and the bogie wheel. The arm couples the bogie wheel to the frame, and exerts a predetermined force against the bogie wheel, and thus the track. The arm can include a composite material, such as fiberglass, and can form a spring member that couples the bogie wheel to the frame in a cantilever configuration.
Preferably, the bogie wheel is movable with respect to the frame, and pivots with respect to the frame. The arm bends as the bogie wheel moves or pivots. The bogie wheel and the continuous track can have an initial position with respect to the frame on a flat riding surface, while the arm is bent into a curved configuration to bias the bogie wheel and continuous track towards the riding surface, so that the arm is pre-loaded.
In accordance with one aspect of the present invention, the vehicle or kit includes a ski coupled to the frame or a front fork of the frame.
In accordance with another aspect of the present invention, the track assembly advantageously can include a tensioner to maintain tension on the continuous track. The tensioner can include a bogie bracket attached to the flexible arm opposite the frame. A pivot bar has a first end pivotally attached to the bogie bracket, and a second end coupled to the bogie wheel. The pivot bar is pivotal towards and away from the frame, but biased away from the frame to maintain tension on the track. For example, a spring can be coupled to and between the bogie bracket and the pivot bar to pull the pivot bar away from the frame and tension the track.
In accordance with another aspect of the present invention, the vehicle has at least two configurations, including a wheeled configuration and a tracked configuration. In the wheeled configuration, a rear wheel is coupled to the rear fork, and the track assembly is uncoupled from the frame. In addition, a front wheel can be coupled to the front fork, and the ski can be uncoupled from the front fork. In the tracked configuration, the track assembly is coupled to the frame, and the rear wheel is uncoupled from the rear fork. In addition, the ski can be coupled to the front fork, and the front wheel uncoupled form the front fork.
Additional features and advantages of the invention will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the invention.